Radiused Lifters.

Is there any advantage to having the lifters ground with a radius even though the camshaft does not require it?

Is there less wear and longer cam life or is it a waste of money?

I will be using a 2S cam in my 850 Commando.

Apart loosing some duration, which could be good or bad depending of your cam , i don't know !!! plus according to the radius , that could be different too, for example , I had fitted a 5 S cam (similar JS1 or 560 -NR) with BSA lifters and I was happy , but I was totally ignorant of what I had done at that time , so your question is a good one ........and like you I am waiting for clever answers , thanks to have posted it !!

https://www.accessnorton.com/NortonCommando/high-rpm-rx-cam-for-radiused-lifters.19210/
more info there .........

My (limited) understanding is that you could put a 3”or 4” radius on your followers with that cam without any problems.

It would knock a little peak HP off of the top and give a little more mid range by lowering your powerband by 500rpm or so, making it a little more ‘streetable’.

As to whether or not a radius is better for cam wear / life etc I don’t know. My totally uneducated gut feel is that two radiused surfaces coming together would create a greater oil ‘wedge’ between the surfaces. However, those with more knowledge have explained that it ain’t as simple as that.

I’d say it depends what you want it for. Peak hooligan performance? keep flat followers. A little more streetable? Radius the followers.

FWIW I’m putting my Web Cam equivalent of a 2S in my 920 with flat followers.

Hooligan....

Thanks for the interesting answers.

arch said:

Is there any advantage to having the lifters ground with a radius even though the camshaft does not require it?

Is there less wear and longer cam life or is it a waste of money?

I will be using a 2S cam in my 850 Commando.

Click to expand...

This megacycle cam is very close to a combat.
solid lines are flat lifters
dashed lines are with 3" radius lifters
The total lift is unchanged (must remove insulators under intake springs)
The mid part is "truncated" narrower and therefore reduces the over lap.
flat overlap @about .175"
radiused overlap @about .150"

correct per Fast Eddie:
"It would knock a little peak HP off of the top and give a little more mid range by lowering your powerband by 500rpm or so, making it a little more ‘streetable’."

What valve clearances are you using with the megacycle cam?...I think they spec 16 inlet and exhaust, seems a lot to me?....what is your opinion?....talking about the stage one cam.......Thanks